I'm upgrading an old web application to use Infragistics v14.1 from v7.2, but it appears that the Infragistics.WebUI.UltraWebGrid component is no longer there.
Has the UltraWebGrid moved into a different library, replaced by something else, or removed completely?
I'm new to Infragistics, so I'm very unfamiliar with the various components.
In version 11.2 the control WebGrid together with other controls has been retired by Infragistics and replaced by controls built using Infragistics ASP.NET AJAX framework and jQuery. So, yes the WebGrid is no more available in 14.1
The new control that replaced the WebGrid is called WebDataGrid or WebHierarchicalDataGrid
You can find more information on their web site in the Breaking changes of the Documentation pages.